An able wildlife author-photographer (The Raggedy Red Squirrel, 1992) portrays a young gray kangaroo from the time he first peeks from his mother's pouch until he's supplanted by her next newborn. Ryden's color photos are splendidly detailed; her informative text adds details such as the joey's earlier life and interprets such appealing closeups as his reaching from the pouch to sample grass, boxing with a companionable half-grown older brother (an important learning experience), diving head-first into the pouch, and finally, rather comically, outgrowing it. Photos of other animals add a sense of the kangaroo's place in its habitat; a concluding note explains the place of Macropus fuliginosus in the animal world. An enchanting animal portrait. (Nonfiction. 4-9)